We are investigating several aspects of the physiology of the neuromuscular junctions. 1) Using a two electrode technique. We are attempting to localize sites of ACh action in the end-plate membrane as indicaters of the sites of ACh release from the nerve terminal. We are particularly interested in whether or not a greater length of terminal is involved in release during facilition. 2) We are studying the effects of prior exposure to different temperature on the amplitude of miniature end-plate potentials. The evidence to date suggests that appropriate treatment at low temperatures increases the amount of acetylcholine/quantum, while treatment at low temperatures decreases the amount of acetylcholine/ quantum.